On Sat, Mar 19, 2011 at 09:45:00AM -0400, Christoph Hellwig wrote: > On Fri, Mar 18, 2011 at 03:06:48PM +1100, Dave Chinner wrote: > > It gets used by a second caller in the next patch that uses a > > timeout of zero. The idea of adding a delay to a normal push is to > > rate limit the number of times we do work so we always work on > > batches rather a few items at a time in multiple executions of the > > work. > > > > I'll see if it's simpler to just do this work directly in teh > > callers, though. > > I don't think hiding this delay (uncommented) in the workqueue use is > a good idea. FWIW, we already have an implicit delay for frequent callers when the AIL is busy - the uninterruptible sleep for sleeps of <= 20ms. That was implemented specifically to rate-limit wakeups while the xfsaild was busy pushing. This is essentially a different implementation of the same mechanism. > xlog_grant_push_ail has all the logics about when to push > the AIL, so any batching should be grouped with that logic, and > documented there. It in fact already has some comments static that > a min/max watermark scheme would be useful. Yes, it does, but that's a much bigger change that has some potentially nasty problems like ensuring the watermarks are always a sane distance apart which is difficult to do on small logs were a single transaction reservation can easily be larger than 10% of the log. Hence watermarks are a much harder change to validate and tune compared to a simple push wakeup rate-limit... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
